JP4162105B2 - Outboard motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a ship in which the engine is cooled by the cooling water sucked from the lower part, and air is supplied to the combustion chamber of the engine through the intake passage, and the injector injects fuel into the air in the intake passage. It relates to the external machine.
[0002]
[Prior art]
A conventional engine intake passage is disposed between an intake port of a combustion chamber and a surge tank, and a throttle body is provided at an air inflow portion of the surge tank. The throttle body adjusts the amount of air flowing into the surge tank, and supplies this air from the surge tank to the combustion chamber via the intake passage. An injector for injecting fuel into the air in the intake passage is provided near the intake port of the combustion chamber. And the engine is cooled with the cooling water sucked from the lower part of the outboard motor.
[0003]
[Problems to be solved by the invention]
By the way, the cooling water sucked from the lower part of the outboard motor flows while meandering up and down from the lower part of the engine, and the temperature of the lower part of the engine is lower than the temperature of the upper part. Therefore, the fuel injected from the injector is easier to evaporate in the upper intake passage than in the lower intake passage, and is better diffused and mixed with the air to improve the combustion efficiency. As a result, the output of the upper cylinder tends to increase compared to the lower cylinder, and the engine output may vary relatively greatly depending on the cylinder.
[0004]
An object of the present invention is to provide an outboard motor in which the difference between the combustion efficiency of the upper cylinder and the combustion efficiency of the lower cylinder is small.
[0005]
[Means for Solving the Problems]
In the outboard motor of the present invention, the engine (9) is cooled by the cooling water sucked from below, and the engine is covered by the cowling (1, 2). The crankshaft (10) of the engine is arranged in the vertical direction, a plurality of cylinders (11) are arranged in the vertical direction behind the crankshaft, and the combustion chamber (11a) side of the cylinder is covered with the cylinder head (22). It has been broken. In this cylinder head, an intake port (33) that opens to the combustion chamber of the cylinder is formed for each combustion chamber, and a silencer (51) is provided at the front portion in the cowling. The silencer and the cylinder head An intake passage (53) is provided for each combustion chamber. An injector (56) for injecting fuel is attached to an intermediate portion of the intake passage. On the downstream side of this injector, the inclination of the lower intake passage is larger than the inclination of the upper intake passage, and the distance between the injector and the intake port in the lower intake passage is the same as that in the upper intake passage. It is longer than the distance between the injector and the air intake.
[0006]
In some cases, a throttle body (41) is provided at an intermediate portion of the intake passage, and an injector is attached to the throttle body.
[0007]
Furthermore, a pair of upper and lower intake ports may be formed for each combustion chamber.
[0008]
A cylinder is arranged in a substantially V shape on the left and right sides of the crankshaft, and a plurality of cylinders are arranged in the vertical direction. A throttle body is provided in the middle of the intake passage. In addition, an injector for injecting fuel is attached, the valve shaft of the throttle valve (42) of the throttle body is arranged in the vertical direction, and the valve shaft of the uppermost throttle valve is above the engine case In some cases, the upper ends of the valve shafts of the left and right throttle valves are connected and interlocked by an interlocking mechanism (66, 67) disposed above the engine case.
[0009]
In this specification, the cylinder arrangement side with respect to the crankshaft is referred to as “rear side”.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, a first embodiment of the outboard motor according to the present invention will be described with reference to FIGS. FIG. 1 is a sectional view of an outboard motor according to the present invention as seen from the side. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a plan sectional view of the upper portion of the outboard motor according to the first embodiment. FIG. 4 is a plan view of the inside of the outboard motor according to the first embodiment. FIG. 5 is a schematic diagram of the flow of cooling water. FIG. 6 is an enlarged view of a main part of the intake passage. 7A and 7B are plan views of the drive mechanism of the throttle valve, in which FIG. 7A is a diagram of the first embodiment, and FIG. 1 and 2, the engine is shown in a partially cutaway side view. 3 and 4, the vapor separator tank is indicated by a broken line. In FIG. 4, the drive mechanism of the throttle valve is not shown.
[0011]
The outboard motor is covered with a housing including an upper cowling 1, a lower cowling 2, an upper casing 3, and a lower casing 4 in order from the upper side. A cooling water intake 5 is formed in the lower casing 4. A mounting bracket 6 for mounting the outboard motor on the small boat is fixed to the transom 7 of the small boat. An outboard motor main body is rotatably attached to the rear portion of the mounting bracket 6 via a pivot shaft 8 or the like.
[0012]
Inside the cowlings 1 and 2 including the upper cowling 1 and the lower cowling 2, a fuel injection type V-type six-cylinder four-cycle engine 9 as an internal combustion engine is disposed. The crankshaft 10 of the four-cycle engine 9 is provided with a substantially vertical axis, that is, in an up-and-down direction, and a pair of left and right cylinders 11 are distributed in a V-shape in the left-right direction behind the crankshaft 10. Has been placed. This pair of left and right cylinders 11 is provided in three stages in the vertical direction, and a total of six cylinders 11 are arranged. Further, six pistons 13 are connected to the crankshaft 10 via connecting rods 14, and the pistons 13 are slidably disposed inside the cylinders 11. The case 17 of the engine 9 covers the cylinder block 20 that forms the above-described six cylinders 11, the crankcase 21 that covers the crankshaft 10 side of the cylinder block 20, and the combustion chamber 11 a side of the cylinder block 20. It consists of a pair of left and right cylinder heads 22 that close.
[0013]
The lower end of the crankshaft 10 extends from the engine case 17 and is connected to a drive shaft 26 disposed in the upper casing 3. The rotation of the drive shaft 26 is transmitted to a propeller 28 that is rotatably provided at the rear end portion of the lower casing 4 via a bevel gear or the like. A cooling water pump 29 is provided at an intermediate portion of the drive shaft 26 and is driven by the rotation of the drive shaft 26.
[0014]
The cylinder head 22 is formed with an intake passage 31 for supplying air to the cylinder 11 and an exhaust passage 32 for exhausting the combustion gas of the cylinder 11 for each cylinder 11. A pair of upper and lower intake ports 33 at the tip of each intake passage 31 are provided and open to the combustion chamber 11a. Similarly, a pair of upper and lower exhaust ports 34 at the tip of each exhaust passage 32 are provided and open to the combustion chamber 11a. An intake valve 35 opens and closes the intake port 33 of the combustion chamber 11a, and an exhaust valve 36 opens and closes the exhaust port 34 of the combustion chamber 11a. In addition, each intake passage 31 is bifurcated at the intake port 33 side, that is, the downstream side, and communicates with each intake port 33, while the upstream side merges into one. The exhaust passage 32 of the cylinder head 22 communicates with a collective exhaust passage 38 extending in the vertical direction, and combustion gas flowing through the upper and lower exhaust passages 32 flows into and joins the collective exhaust passage 38. The collective exhaust passage 38 is provided in a pair on the left and right sides and is disposed at the rear portion of the cylinder head 22.
[0015]
A throttle body 41 is connected to the upstream end of each intake passage 31 of the cylinder head 22 via an intake manifold 37. The throttle body 41 is provided with a throttle valve 42 with the valve shaft up and down to adjust the amount of air flowing. The throttle body 41 is connected to a rear end portion of a resin intake pipe 46. The intake pipe 46 extends forward from the throttle body 41, and the front end portion is connected to a resin silencer 51 disposed at the front portion in the cowlings 1 and 2. Three intake pipes 46 are provided in the vertical direction on the left and right sides. The resin intake pipe 46 and the silencer 51 are assembled to the engine body after being connected by welding, fitting, adhesive, or the like.
[0016]
In this way, the intake passage 53 of the cylinder head 22, the intake manifold 37, the throttle body 41, and the intake pipe 46 constitute an intake passage 53 from the silencer 51 to the intake port 33 of the combustion chamber 11 a. In the plan view (that is, viewed from the front end side of the crankshaft 10), the intake passage 53 extends outward from the intake port 33 of the combustion chamber 11a to form an overhang passage portion 53a, and then a silencer A connecting passage portion 53 b that extends toward 51 and has a front end connected to the silencer 51. The overhang passage portion 53 a includes the intake passage 31 of the cylinder head 22 and the intake manifold 37. The connection passage portion 53 b is composed of a throttle body 41 and an intake pipe 46.
[0017]
In the side view of the intake passage 53, the overhang passage portion 53a is inclined forwardly upward from the intake port 33 of the combustion chamber 11a, so that the throttle body 41 is substantially horizontal, and the intake pipe 46 is upwardly raised from the throttle body 41. It is inclined to. The inclination of the overhang passage portion 53 a and the intake pipe 46 is gentler in the upper intake passage 53 than in the lower intake passage 53.
[0018]
The throttle body 41 is provided with an electronically controlled injector 56 for each intake passage 53. The injector 56 has an injection port communicating with the intake passage 53 and is disposed between the engine case 17 and the intake passage 53. A fuel such as gasoline is supplied from the injector 56 to the air in the intake passage 53. By the way, as described above, the intake passage 53 is inclined rearwardly downstream from the injector 56, and the inclination of the lower intake passage 53 is larger than that of the upper intake passage 53. Therefore, the distance between the injector 56 and the intake port 33, that is, the length of the flow path, is longer in the lower intake passage 53 than in the upper intake passage 53. Further, the vertical distance between the axial centers of the injectors 56 is smaller than the vertical distance between the centers of the intake ports 33 for each combustion chamber 11a.
[0019]
An ISC (idle speed control) 57 that is an intake system component that adjusts the flow rate of air to reduce rotational fluctuation during idling is attached to the upper side of the engine case 17, and an air supply flow path 58 from the ISC 57 is Each throttle body 41 is connected. During idling, air is supplied from the ISC 57 into the throttle body 41. Reference numeral 61 is a starter motor, reference numeral 62 is a vapor separator tank, and reference numeral 63 is a spark plug.
[0020]
Three throttle bodies 41 are arranged vertically on the left and right sides of the engine case 17, and the valve shafts of the throttle valves 42 of the upper and lower throttle bodies 41 are connected to each other and interlocked with each other. An upper end portion of the valve shaft of the uppermost throttle valve 42 protrudes upward from the engine case 17 and a lever 65 is fixed. The lever 65 is connected to a rotating plate via a link 66 or the like. 67. The rotating plate 67 is rotatably attached to the upper side of the engine case 17. When a throttle lever (not shown) is operated, as shown in FIG. 5A, the throttle lever 101, the cam lever 102, the L-shaped sliding lever 103, the rod 104, and the like are driven. The moving plate 67 is rotated. The rotation of the rotation plate 67 is transmitted to the lever 65 fixed to the valve shafts of the left and right throttle valves 42 via the left and right links 66, and the valve shaft of the throttle valve 42 is rotated. In this way, when the valve shaft of the throttle valve 42 rotates, the amount of air flowing through the throttle body 41 is adjusted.
A modification of the drive mechanism is shown in FIG. In this modification, when the throttle lever is operated, the rotating plate 67 is rotated via the throttle cable 101, the cam lever 102, the sliding lever 106, the pair of wires 107, and the like.
[0021]
A camshaft drive pulley 71 is provided at the upper end of the crankshaft 10, and a driven pulley 73 is provided at the upper end of the camshaft 72 that drives the exhaust valve 36. A belt 76 is stretched around the camshaft drive pulley 71 and the driven pulley 73. A tensioner 78 is provided to apply tension to the belt 76. The aforementioned link 66 that constitutes a part of the throttle interlocking member that drives the valve shaft of the throttle valve 42 is disposed in a space between the engine case 17 and the belt 76.
[0022]
In the outboard motor configured as described above, when the crankshaft 10 rotates, the air in the cowlings 1 and 2 is sucked into the silencer 51, and the sucked air is sucked into the intake pipe 46, the throttle body 41, and the intake manifold. 37 and the intake passage 31 of the cylinder head 22 and flows into the combustion chamber 11 a of the cylinder 11. In the throttle body 41, fuel such as gasoline injected from the injector 56 is mixed with the air flowing through the throttle body 41, the intake manifold 37 and the intake passage 31. Further, the fuel gas mixture that has flowed into the combustion chamber 11a is ignited by the spark plug 63 and burned. The exhaust gas generated at this time is the exhaust passage 32, the collective exhaust passage 38 and the casings 3 and 4 of the cylinder head 22. Are discharged from the boss of the propeller 28 and the like. The piston 13 reciprocates due to the expansion force when the fuel gas mixture burns, and the crankshaft 10 rotates through the connecting rod 14 due to the reciprocating motion of the piston 13.
[0023]
Further, the rotation of the crankshaft 10 causes the cooling water pump 29 to operate, and the water outside the outboard motor, that is, the cooling water, is sucked from the cooling water intake 5 of the lower casing 4 as shown in FIG. The sucked cooling water rises toward the engine 9 through the rising flow path 81. A pressure control valve 83 is provided in the middle of the ascending flow path 81 so as to communicate therewith. The pressure control valve 83 discharges the cooling water in the rising flow path 81 when the cooling water pressure becomes equal to or higher than the set pressure, and sets the pressure in the rising flow path 81 to the set pressure. The cooling water that has flowed into the engine 9 passes through the exhaust passage cooling water passage 86 around the exhaust passage 32 for each combustion chamber 11 a in the cylinder head 22, and then the collective exhaust passage cooling water passage 87 around the collective exhaust passage 38. The cylinder head 22 flows through the combustion chamber cooling water passage 88 around the combustion chamber 11 a, the V bank jacket 89 inside the cylinder block 20, and the cylinder cooling water passage 91 around the cylinder 11 in the cylinder block 20. Has reached. The thermostat 93 allows the flow of the cooling water when the temperature of the cooling water becomes equal to or higher than the set temperature, and substantially blocks the flow of the cooling water when the temperature is lower than the set temperature (a trace amount is flowing). ). The thermostat 93 prevents the engine 9 from being overcooled by the cooling water. And the comparatively high temperature (for example, 60 degreeC or more) cooling water which flowed out from the thermostat 93 is discharged | emitted out of the outboard motor through the water channel 96 after cooling. In this way, the cooling water having a relatively low temperature sucked from the outside of the outboard motor flows from the lower part of the engine 9, meanders up and down, and then drained out of the outboard motor. Therefore, the lower temperature of the engine 9 is lower than the upper temperature.
[0024]
As described above, in the first embodiment, the distance from the injection port of the injector 56 to the intake port 33 of the combustion chamber 11a, that is, the length of the flow path, is the shortest in the upper intake passage 53, It becomes longer as it goes down sequentially. Therefore, the arrival time of the fuel injected from the injector 56 to the intake port 33 is shorter in the upper intake passage 53 than in the lower intake passage 53. Further, the cooling water flows in from the lower side of the engine 9 and meanders up and down. The temperature of the upper part of the engine 9 is higher than the temperature of the lower part of the engine 9, and the upper intake passage 53. It is easier for the fuel to evaporate. Therefore, the rate per unit time at which the fuel injected from the injector 56 diffuses into the air is larger in the upper intake passage 53 than in the lower intake passage 53. However, as described above, the arrival time to the intake port 33 is shorter in the upper intake passage 53 than in the lower intake passage 53, and the diffusion of fuel at the time when the intake port 33 is reached. The ratio is reduced when a large difference occurs between the upper intake passage 53 and the lower intake passage 53. As a result, it is possible to prevent a large difference between the output in the upper cylinder 11 and the output in the lower cylinder 11, and the engine 9 can operate stably.
[0025]
In addition, a pair of upper and lower intake ports 33 of the combustion chamber 11 a are provided, and the upper intake passage 53 has a smaller inclination than the lower intake passage 53. Therefore, as shown in FIG. 6, the upper intake passage 53 has a smaller difference in air volume between the upper intake port 33a and the lower intake port 33b in each combustion chamber 11a. Therefore, a spiral flow (so-called swirl) from the upper intake port 33a to the lower intake port 33b in the combustion chamber 11a is smaller in the upper intake passage 53. The larger the swirl, the higher the fuel combustion efficiency in the combustion chamber 11a of the cylinder 11. Therefore, considering only the swirl, the lower cylinder 11 has a higher combustion efficiency than the upper cylinder 11. Due to this swirl difference, the difference in combustion efficiency between the cylinders 11 due to the temperature difference between the upper part and the lower part of the engine 9 can be compensated as much as possible.
[0026]
Further, on the downstream side of the throttle body 41, the intake passage 53 is inclined rearwardly downward, and the inclination of the lower intake passage 53 is larger than that of the upper intake passage 53. Therefore, the upper and lower intervals of the throttle body 41 can be reduced as compared with the case where the upper intake passage 53 and the lower intake passage 53 are arranged substantially in parallel with the arrangement of the intake ports 33. As a result, the entire throttle body assembly from the lowermost throttle body 41 to the uppermost throttle body 41 can be reduced in height and compact.
[0027]
Further, the intake pipe 46 is inclined rearwardly downward, and the inclination of the lower intake pipe 46 is larger than the inclination of the upper intake pipe 46. A large space can be formed. Accordingly, components such as the vapor separator tank 62 can be disposed below the front portion of the intake pipe 46. As a result, the space below the intake pipe 46 can be used effectively.
[0028]
A throttle body 41 is provided in an intermediate portion of the intake passage 53, and a resin intake pipe 46 and a silencer 51 are attached to the front side, that is, the upstream side of the throttle body 41. In this way, the throttle body 41 that adjusts the amount of flowing air is disposed on the downstream side of the intake pipe 46 and the silencer 51, so that outside air flows from the connection portion between the intake pipe 46 and the silencer 51, etc. Even if the air flows into the silencer 51, the flow rate of air on the downstream side of the throttle body 41 hardly fluctuates. Therefore, the mounting accuracy of the intake pipe 46, the silencer 51, etc. can be lowered, and mounting work and processing work are facilitated.
[0029]
Further, after assembling the intake pipe 46 and the silencer 51, the assembled intake pipe 46 and silencer 51 are attached to the engine body. Therefore, the intake pipe 46 and the silencer 51 are unitized, and the assembly work of the engine 9 becomes easy.
[0030]
Furthermore, since the injector 56 is attached to the throttle body 41, the throttle body 41 and the injector 56 can be unitized. Therefore, the injector 56 and the throttle body 41 can be attached in a united state, and the time required for the assembly work of the engine 9 can be shortened. As a result, man-hours in the engine assembly line can be reduced.
[0031]
The ISC 57 is disposed on the upper side of the engine case 17, and air is supplied from the ISC 57 to the left and right throttle bodies 41 via the air supply flow path 58. Therefore, a single ISC 57 can supply air to a large number of throttle bodies 41 during idling.
[0032]
Further, the valve shaft of the throttle valve 42 of the throttle body 41 is arranged in the vertical direction, and the valve shafts of the left and right uppermost throttle bodies 41 are connected to the interlock mechanism (rotating plate 67, link 66, etc.) above the engine case 17. It is linked via Therefore, the interlocking mechanism hardly protrudes from the lateral side of the engine 9 to the outside, and the lateral width of the cowlings 1 and 2 can be made compact.
[0033]
Next, a second embodiment of the outboard motor according to the present invention will be described. FIG. 8 is a plan sectional view of the upper part of the outboard motor according to the second embodiment. In the description of the second embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof is omitted.
[0034]
FIG. 8 is a view corresponding to FIG. 3 of the first embodiment, and the injector 56 is attached to the intake pipe 46 instead of the throttle body 41. In addition, in the first embodiment, the injection port of the injector 56 communicates with the intake passage 53 on the downstream side of the throttle valve 42. In the second embodiment, the injection port is upstream of the throttle valve 42. The injector 56 injects fuel toward the gap between the inner surface of the throttle body 41 and the throttle valve 42. In the gap between the inner surface of the throttle body 41 and the throttle valve 42, the air flow is fast, so that the fuel injected from the injector 56 can be scattered efficiently. Further, the injection direction of the injector 56 does not face upward, and fuel or the like does not accumulate near the injection port of the injector 56.
[0035]
Further, the ISC 57 is provided in each throttle body 41.
Furthermore, since the injector 56 is attached to the intake pipe 46, the injector 56 and the intake pipe 46 can be unitized. Therefore, the injector 56 and the intake pipe 46 can be attached in a united state, and the time required for the assembly work of the engine 9 can be shortened.
The other points such as the point related to the arrival time from the injection port of the injector 56 to the intake port 33 and the point related to the swirl are substantially the same as those in the first embodiment.
[0036]
Next, a third embodiment of the outboard motor according to the present invention will be described. FIG. 9 is a plan sectional view of the upper part of the outboard motor according to the third embodiment. In the description of the third embodiment, the same reference numerals are assigned to the components corresponding to the components of the first embodiment, and the detailed description thereof is omitted. Further, in FIG. 9, the vapor separator tank is indicated by a broken line.
[0037]
FIG. 9 is a view corresponding to FIG. 3 of the first embodiment. In the third embodiment, a portion of the intake manifold 37 is formed integrally with the cylinder head 22. Further, in the plan view (that is, when viewed from the front end side of the crankshaft 10), the intake passage 53 extends outward from the intake port 33 of the combustion chamber 11a to form an overhang passage portion 53a. A retracting passage portion 53c is formed extending inward while being curved, and includes a side passage portion 53d extending toward the silencer 51 from the retracting passage portion 53c. The overhang passage portion 53 a is configured by the intake passage 31 of the cylinder head 22. The lead-in passage portion 53c is constituted by the throttle body 41, and is inclined substantially along the wall 49 of the cylinder 11 so as to become outward as it goes later. The side passage portion 53d is composed of the intake pipe 46 and is disposed substantially along the outer wall 48 of the crank chamber 47 (that is, substantially in the front-rear direction).
[0038]
The injector 56 is attached to the throttle body 41, and its axis is arranged in the front-rear direction (that is, substantially parallel to the outer wall 48 of the crank chamber 47), so that the injector 56 does not protrude outward. Therefore, the lateral width of the cowlings 1 and 2 can be reduced.
[0039]
Further, the injector 56 is disposed outside the intake passage 53, and maintenance such as replacement can be easily performed.
The other points such as the point related to the arrival time from the injection port of the injector 56 to the intake port 33 and the point related to the swirl are substantially the same as those in the first embodiment.
[0040]
Next, a fourth embodiment of the outboard motor according to the present invention will be described. FIG. 10 is a plan sectional view of the upper part of the outboard motor according to the fourth embodiment. In the description of the fourth embodiment, the same reference numerals are given to the components corresponding to the components of the third embodiment, and the detailed description thereof is omitted. Further, in FIG. 10, the vapor separator tank is indicated by a broken line.
[0041]
FIG. 10 is a view corresponding to FIG. 9 of the third embodiment. In the fourth embodiment, the injector 56 is attached to the intake pipe 46 instead of the throttle body 41. Further, in the third embodiment, the injection port of the injector 56 communicates with the intake passage 53 on the downstream side of the throttle valve 42. In the fourth embodiment, the injection port is upstream of the throttle valve 42. The injector 56 injects fuel toward the gap between the inner surface of the throttle body 41 and the throttle valve 42. In the gap between the inner surface of the throttle body 41 and the throttle valve 42, the air flow is fast, so that the fuel injected from the injector 56 can be scattered efficiently. Further, the injection direction of the injector 56 does not face upward, and fuel or the like does not accumulate near the injection port of the injector 56.
The other points such as the point related to the arrival time from the injection port of the injector 56 to the intake port 33 and the point related to the swirl are substantially the same as those in the first embodiment.
[0042]
Next, a fifth embodiment of the outboard motor according to the present invention will be described. FIG. 11 is a schematic diagram of the flow of cooling water according to the fifth embodiment. In the description of the fifth embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof is omitted.
[0043]
FIG. 11 is a view corresponding to FIG. 5 of the first embodiment. In the fifth embodiment, the V bank jacket 89 is divided into left and right by a partition wall 121, and a pair of left and right flow paths 89a. , 89b are formed. Therefore, the left and right thermostats 93 can perform the temperature management of the cylinder 11 independently. The pair of left and right flow paths 89a and 89b communicate with each other at the upper part and the lower part. Further, a pilot water channel 122 is connected to the V bank jacket 89, and a small amount of water flows out from the end of the pilot water channel 122 when the cooling water is normally supplied. Thus, it can be seen that the cooling water is normally supplied by the fact that water is flowing out from the end of the pilot water channel 122. For example, when the cooling water pump 29 fails or the flow path such as the rising flow path 81 is clogged, it is understood that the outflow from the pilot water path 122 stops and the cooling water supply is abnormal.
[0044]
Furthermore, air vent passages 123a, 123b and water drain passages 124a, 124b, 124c are formed so that water can be drained from the cooling water passages 86, 87, 88, 89, 91 when the engine 9 is stopped. The air vent passages 123a, 123b and the water drain passages 124a, 124b, 124c are formed to have a smaller cross section than the cooling water passages 86, 87, 88, 89, 91. The first air vent passage 123a communicates the upper portion of the combustion chamber cooling water passage 88 with the upper portion of the cylinder cooling water passage 91, and the second air vent passage 123b communicates with the upper portion of the combustion chamber cooling water passage 88 and the collective exhaust. The upper part of the cooling water channel 87 for passage is connected. The first drainage passage 124a communicates the lower part of the combustion chamber cooling water channel 88 and the lower part of the cylinder cooling water channel 91, and the second drainage channel 124b communicates with the lower part of the cylinder cooling water channel 91 and the post-cooling water channel 96. The third drainage passage 124 c communicates the lower part of the V bank jacket 89 and the rising flow path 81. Further, an exhaust pipe cooling water passage 126 is connected to the rising flow path 81, and the cooling water in the exhaust pipe cooling water passage 126 cools the exhaust pipe 127. The exhaust pipe 127 is provided in a vertical space formed in the center of the oil pan 128. The fifth embodiment is substantially the same as the first embodiment except for the cooling water channel.
[0045]
Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be done. Examples of modifications of the present invention are illustrated below.
(1) In the above embodiment, the engine is a V-type 6-cylinder 4-cycle engine, but the type, the number of cylinders, and the like can be changed as appropriate. For example, it can be an L-type engine.
[0046]
(2) The arrangement relationship in the left-right direction can be reversed.
(3) The material of the silencer 51 and the intake pipe 46 does not necessarily need to be resin, and can be formed of aluminum die casting or the like.
(4) The driving mechanism is directly connected to the valve shaft of the right or left throttle valve 42, and the driving force from the throttle cable 101 is transmitted to the valve shaft of the right or left throttle valve 42. It is also possible to transmit to the valve shaft of the other throttle valve 42 via the interlocking mechanisms 66 and 67.
[0047]
【The invention's effect】
According to the present invention, the engine is cooled by the cooling water sucked from the lower part of the outboard motor, and the temperature of the lower part of the engine is lower than the temperature of the upper part of the engine. Therefore, the fuel injected from the injector has a lower diffusion efficiency in the lower intake passage than in the upper intake passage. However, on the downstream side of the injector, the distance between the injector and the intake port in the lower intake passage is longer than the distance between the injector and the intake port in the upper intake passage. The time required to reach the mouth is longer in the lower intake passage. Therefore, the time during which the fuel is diffusing becomes longer and the amount of diffusion can be increased. As a result, the difference in the amount of diffusion due to the temperature difference between the upper part and the lower part of the engine can be minimized. And the difference in the combustion efficiency between cylinders can be made as small as possible.
[0048]
Further, when a throttle body is provided in the middle portion of the intake passage and the injector is attached to the throttle body, the injector and the throttle body can be unitized, and the assembly of the engine becomes easy.
[0049]
Furthermore, a pair of upper and lower intake ports may be formed for each combustion chamber. Further, on the downstream side of the injector, the inclination of the lower intake passage is larger than the inclination of the upper intake passage, and the swirl of the combustion chamber leading to the lower intake passage leads to the upper intake passage. It becomes larger than the swirl of the combustion chamber, and the combustion efficiency can be improved. Due to this swirl difference, the difference in combustion efficiency between cylinders due to the temperature difference between the upper and lower parts of the engine can be compensated as much as possible.
[0050]
When the V-type engine is adopted for the outboard motor, when the upper ends of the valve shafts of the left and right throttle valves are connected and interlocked by an interlocking mechanism disposed above the engine case, The interlocking mechanism for interlocking the valve shafts of the left and right throttle valves hardly protrudes to the side, and the lateral width of the cowling of the outboard motor can be made as small as possible.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an outboard motor according to the present invention as viewed from the side.
FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3 is a plan sectional view of an upper portion of the outboard motor according to the first embodiment.
FIG. 4 is a plan view of the inside of the outboard motor according to the first embodiment.
FIG. 5 is a schematic view of the flow of cooling water.
FIG. 6 is an enlarged view of a main part of the intake passage.
7A and 7B are plan views of a throttle valve drive mechanism, in which FIG. 7A is a diagram of the first embodiment, and FIG. 7B is a diagram of a modification.
FIG. 8 is a plan sectional view of an upper portion of an outboard motor according to a second embodiment.
FIG. 9 is a plan sectional view of an upper part of an outboard motor according to a third embodiment.
FIG. 10 is a plan sectional view of an upper part of an outboard motor according to a fourth embodiment.
FIG. 11 is a schematic view of a flow of cooling water according to a fifth embodiment.
[Explanation of symbols]
1 Upper cowling
2 Lower cowling
9 Engine
10 Crankshaft
11 cylinders
11a Combustion chamber
22 Cylinder head
33 Inlet
41 Throttle body
42 Throttle valve
51 Silencer
53 Air intake passage
56 injectors
66 link (interlocking mechanism)
67 Rotating plate (interlocking mechanism)

Claims (4)

In the outboard motor in which the engine is cooled by the cooling water sucked from the lower part and the cowling covers this engine,
The crankshaft of the engine is arranged vertically
A plurality of cylinders are arranged in the vertical direction behind the crankshaft,
The combustion chamber side of this cylinder is covered with a cylinder head,
In this cylinder head, an intake port that opens to the combustion chamber of the cylinder is formed for each combustion chamber,
A silencer is provided at the front of the cowling,
Between this silencer and the intake of the cylinder head, an intake passage is provided for each combustion chamber,
An injector that injects fuel is attached to the middle of the intake passage.
On the downstream side of this injector, the inclination of the lower intake passage is larger than the inclination of the upper intake passage,
An outboard motor characterized in that the distance between the injector and the intake port in the lower intake passage is longer than the distance between the injector and the intake port in the upper intake passage. The outboard motor according to claim 1, wherein a throttle body is provided in an intermediate portion of the intake passage, and an injector is attached to the throttle body. The outboard motor according to claim 1 or 2, wherein a pair of upper and lower intake ports are formed for each combustion chamber. In the outboard motor in which the engine is cooled by the cooling water sucked from the lower part and the cowling covers this engine,
The crankshaft of the engine is arranged vertically
Behind this crankshaft, the cylinders are arranged in a substantially V-shaped manner on the left and right, and a plurality of cylinders are arranged in the vertical direction,
The combustion chamber side of this cylinder is covered with a cylinder head,
In this cylinder head, an intake port that opens to the combustion chamber of the cylinder is formed for each combustion chamber,
A silencer is provided at the front of the cowling,
Between this silencer and the intake of the cylinder head, an intake passage is provided for each combustion chamber,
A throttle body is provided in the middle of this intake passage,
An injector that injects fuel is attached to this throttle body.
The valve shaft of the throttle valve of the throttle body is arranged in the vertical direction, and the valve shaft of the uppermost throttle valve projects upward from the engine case,
The upper ends of the valve shafts of the left and right throttle valves are linked and linked by an interlocking mechanism arranged above the engine case.
On the downstream side of the throttle body, the inclination of the lower intake passage is larger than the inclination of the upper intake passage,
An outboard motor characterized in that the distance between the injector and the intake port in the lower intake passage is longer than the distance between the injector and the intake port in the upper intake passage.

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